Apparatus for bending glass



2 Sheets-Sheet l l 2) LM-.

D. H. GOODWILLIE APPARATUS FOR BENDING GLASS Filed July 5` Oct. 4, 1938.

E luz- 'Patented Oct. 4, 193s UNITED ,STATES PATENT OFFICE David H.Goodwillie,

Toledo, Ghio, assigner to Libbey-Owens-Ford Glas's Company, Toledo,Ohio, a. corporation of Ohio I Application July 5, 1934, Serial No.733,741

' 4 Claims.

'Ihe present invention relates to an improved process and aparatus forbending glass and more particularly for -the bending of flat sheets orplates of glass.

An important object of this invention is the provision of a process andapparatus of the above character wherein the bending of the glass sheetsor plates may be performed in a substantially continuous manner,-thereby reducing handling of the glass to a minimum and acceleratingproduction.

Another important object of this invention is the provision of a processand apparatus of the above character by the practice and use of whichglass (sheets or plates can be accurately bent to apredetermined'curvature ina thoroughly practical and efdcient manner soas to reduce the lia` bility of breakage of the glass and likewiseminimize the setting up of stresses and4 strains therein during thebending operation.

According to theinvention, there is provided a bending furnace or ovenof substantially tunnellike formation wherein a series of moldssupporting the glass sheets or plates to be bent, commonly termed theblanks, are carried upon cars or trucks and moved progressively andpreferably intermittently therethrough. The movement of the 'molds iseii'ected in a direction longitudinally of the fur-v naceand causes theblanks to pass successively i 3o through a plurality of zones ofdifferent temperatures whichinsures the proper heating, bending, andsubsequent cooling of the said blanks.

Other objects and advantages of the invention will become more apparentduring the course of the following description when taken in connectionwith the accompanying drawings.

In the "drawings wherein like numeralsare" employed to 'designate likeparts throughout the same, 4

40 n Fig. 1 is a side elevation of a continuous bending furnace or Vovenconstructed in 'accordance with the present invention;

Fig. 2 is a plan view thereof, A Y YFig. 3 is a vertical section :takensubstantially on lines-301mg. 1, y l v fFig. 4 is a vertical sectiontaken substantially on line 4 4 of Fig. l, y 4 l Fig. 5 is a verticalsection taken substantially 'on line `5 5 of Fig. 1,

5o Fig. s is a vertical sebtiontaken substantially Fig. '1 is averti'calsection taken substantially 'n `une .v1-7 1 vif Figi. y ,y I y yReferring fnow to the drawings and especially to ,55 mg 1 and 2, thecontinuous bending furnace 0r oven illustrated 4therein is oftunnel-like formation and of considerable length, said furnace beingdivided longitudinally into a plurality of successive portions orsections I0, I I, I 2, I3 and I4 respectively, said sections followingone an- 5 other from the intake end of the furnace to the outlet endthereof. 'The numeral I0 designates the preheating section in which themolds and blanks are adapted to be preheated or, in other words,gradually heated up to facilitate the -sub- 10 sequent bendingoperation. The numeral II designates the bending section whereintheblanks are subjected to a bending heat, the temperature within thissection of the furnace being suff ciently high to cause the blanks todrop by their l5 own Weight into and take the shape of the molds as willb'e more fully hereinafter described. Following the bending section I Iare the cooling sections I2, I3 and III through which the molds aresuccessively moved subsequent to the bending 20 operation and in whichthe blanks are slowly annealed and cooled to avoid breakage thereof asWell as minimize the setting up of stresses and strains therein.

Generally speaking, each section of the furnace 25 comprises oppositeside walls and a crown or roof cooperating to form a substantiallyclosed tunnel chamber, with the chambers of the several sections beingin alignment with and constituting substantial continuations of oneanother so that 30' the cars or trucks carrying the molds and blanks canbe passed in a substantially straight path therethrough.

With vreference particularly to Fig. 7, the bend;- ing section II o`fthe furnace comprises the spaced 35 side wallsIS and I6 respectively'and a crown I'l forming th'itunnel chamber` '18, said'side walls ``andcrown being" preferably `covered with a layer of suitable insulatingmaterial VI9,

Arranged within the chamber I8 and extending 40 longitudinally thereofare the spaced parallel partition walls `2|) and 2l definingtherebetween a way for-'the trucks or cars 2.2 upon which are sup'-ported the molds l3 carrying the glass blanks 24. The trucks 'i2 aremounted'u'pon wheelsZS rolling 'along rails 26 extending longitudinallythrough the furnace and embedded within the 'cement floor 21. i y A I em'ol'd 231s hereinshown as being a concave 50 meld but it win be radilyappreciated that convex molds may also be employed.l vlliike'wi'se, thatthe mol'dsmay be of. any preferred size and shape "to give the `desiredcurvature to the iinish'ed blanks. By using the proper form of mold, any4|55 desired type of curve, either simple or compound, can be formed.

The partition Walls 20 and 2| are spaced from the side walls I5 and I6respectively of the bending section and cooperate therewith to providerelatively narrow channels intowhich the gas flames for heating thefurnace are adapted to be directed, the said channels communicating withthe vault above the truck 22 by passageways formed between the crown I'Iand the tops of the said partition walls 20 and 2|. The heating flamesare adapted to be introduced into the channels from a plurality ofburners 28 arranged along each side of the bending section II andoperating through openings 29 in the side walls I5 and I6. The partitionwalls 20 and 2| therefore serve to protect the trucks and molds from thedirect action of the heating flames.

The bending section of` the furnace is adapted to be heated to arelatively high temperature and in order to prevent the trucks 22 frombeing adversely affected by this intense heat, means is preferablyprovided for circulating a cooling medium beneath the said trucks toprevent overheating,r thereof. This is herein accomplished by theproviison of the conduits 30 and 3I communicating at their inner endswith the space beneath the said trucks. Relatively cool air can then becontinuously circulated beneath the trucks, being introduced preferablyinto one end of the bending section |I of the furnace through oneconduit and withdrawn at the opposite end thereof through the otherconduit,

A transverse sectional view through the preheating section I of thefurnace is shown in Fig. 6 and upon reference thereto, it will be seenthat this furnace section also comprises spaced side walls 32 and 33 anda crown 34 forming a chamber 35 through which the trucks 22 carrying themolds and blanks are passed. The preheating section I0, however, ispreferably not quite as wide as the bending section II and the chamber35 therein is of. a width substantially equal to the width of the saidtrucks.

In order to effect the desired preheating of the molds and blanks asthey are carried through the preheating section, meansv is provided forwithdrawing a certain amount of the heat from the bending section II andutilizing this heat to carry out the preheating operation. To this end,there is arranged at desired locations along each side of the preheatingsection of the furnace a plurality of vertical stacks 36 whichcommunicate with the chamber 35 by means of pipes 31 passinghorizontally through openings 38 in the side Walls 32 and 33 thereof,Associated with each stack is ahorizontally slidable damper 39 and byproperly adjusting these dampers to regulate the draft of the stacks, adraft will be created within the chamber 35 sufficient to withdraw aportion of the heat from the chamber I8 of. the bending section I I andcause it to flow longitudinally through 'the chamber 35 ofthe preheatingsection in adi'rection opposite tothe direction of .movementofftheblanks therethrough. As a result, thev temperature` withinV thepreheating chamber .will increase-,gradually from the forward endthereof toward the: bending section so that the blanks in passingtherethrough will be gradually heated up.

witha relatively narrower extension 40 and,v ifl desired, there may beassociated withvthis extension stacks 4I, similar to stacks 36, incommunication with the interior of the extension and serving to withdrawa portion of the heat from the bending section II, thereby tending tocounteract to some extent the withdrawal of, the heat from said sectionby the action of the stacks 35 and resulting in moreuniforrn temperatureconditions within the said bending section.

As brought out hereinabove, after the molds and blanks leave the bendingsection II of the furnace, they are adapted to be carried successivelythrough the cooling sections I2, I3 and I4 wherein the said blanks areproperly annealed and cooled, so that upon leaving the furnace they maybe readily handled. The first cooling section I2 comprises, asillustrated in Fig. 3, spaced side walls 4I and 42 and a substantiallyflat roof 43 defining the tunnel chamber 44, said side walls and roofbeing preferably covered with a layer of suitable insulating material45. The cooling section I2 is preferably of substantially the same widthas the preheating section I0.

The cooling section I3 (Fig. 4) comprises the spaced side walls 46 and41 and a flat roof 48 defining a. tunnel chamber 49 through which theblanks are carried. The layer of` insulating material 45 covering thecooling section I2 is omitted from the cooling section I3. The finalcooling section I4 is of substantially the same width as the coolingsection I3 and comprises (Fig. spaced side walls 50 and 5I and a roof 52defining the tunnel chamber 53. The roof 52 is relatively thinner thanthe roof of the adjacent cooling section I3 and may be supported at aplurality of spaced points by transverse I-beams 54. By constructing thecooling sections I2, I3 and I4 of the furnace in the manner describedabove, it will be readily apparent that the insulating effect thereof isgradually decreased toward the exit end of the furnace, as a result ofwhich the dissipation of heat from successive cooling sections will beincreased so that the blanks will be gradually cooled as they passtherethrough and upon issuing from the furnace will be reduced to atemperature where they are set and can be readily handled.

In operation, the trucks 22 with thermolds 23 thereon are periodicallyintroduced into the receiving chamber 55 at the entrance end of thefurnace and passed therefrom first 'into the preheating section III. andthence successively through the bending section II and cooling sectionsI2, I3 and I4.. The flat sheets or plates of glass 24 to be bent, andherein termed the blanks, are placed horizontally upon the tops vof themolds as shown in Fig. 6. The trucks are then passed into and throughthe preheatingsection I0 wherein the said molds and likewisethekblanksare gradually heated up to a temperature where they can be introducedinto the bending 4 section Without undergoing any sudden shockwhichmight tend to break or otherwise adversely affect the same. As broughtout above, thepreheating section II! is heated by withdrawing a portionof the heat from the bending sectionLI-ILI and the blanks vare graduallyincreased in :temperature as they pass through thepreh-'eatin'gviwfsection, so that when they enter the bendihgfisction,the temperature thereof will be in thervei'ghborhood of from 1175 to1225 degreesdFahenhe'it. The trucks carrying the blanks are' preferablypassed intermittently through the,j,furnace'with the said trucks beingpermitted to*` remain in the' same position for the desired lengthvoftime dearchers f B pending up the temperatures therein, the length ofthe furnace, etc.

The preheated blanks, upon entering the bending section Il, are ladaptedto be subjected to bending temperatures and when the blank reachesbending heat, the central portion ,thereof will sag or sink down intothe mold by its own weight so that the curvature ,of the mold will beaccurately imparted t'o the blank. 'Ihis softening and set- `tling downof the blank into the mold as it is contained Within thebending sectionil will cause y \\the said blank to be brought into contact with the v,mold throughout its entire area and the desired J dling temperature, 'Asexplained hereinabove,

The blanks,4 upon leaving thebending section,

are carried successively through the cooling sec- I v tions .|2, i3 andi4 in the manner set forth above to anneal the same and reduce them to ahanany desired type of curvature, either'simple or compound, can beformed by using the proper mold. Also, that while a concave mold hasbeen illustrated'herein by way' of example, convex molds can be employedif desired.

- Although entirely satisfactory results can ordinarily be obtainedsimply by heat treating the blanks to cause them to drop by their ownweight into and take the shape of the molds, yet in some instances andespecially when compound curves are being formed, it has been found thatthe blanks, upon sinking into the molds, do` not accurately fit the saidmolds throughout their en tire areas. -This condition is illustrated, byway of example, in Fig. 7. Therefore, in order to avoid s objectionablefeature should it occur, the present invention contemplates theprovision of means for eifecting an additional positive mechanicalpressing of l'the blanks into the molds to assure that the said blankswill be brought into intimate contact with the said molds throughouttheir entire areas.

This mechanical pressing is preferably performed upon the blankimmediately upon its leaving the bending section II, and to this end theroof I3 of the cooling section l2 is provided with a substantiallyrectangular opening 56 (Fig. 3) and adapted to operate through thisopening is the vertically movable forming member or plunger 51, thebottom 58 thereof being of a curvature to conform with the curvatureofthe upper surface 59 of the mold 423. As each succeeding blank 2C isbrought, to a'position beneath the plunger 51, it-will 'be operated onby the said plunger tocause the said blank to assume the shape of themold and plunger, thereby making sure that the blank will have exactlythe same curvature as the mold.

Any suitable means may be provided for indexing the trucks carrying themolds through the furnace so that each truck will be brought to exactposition beneath the plunger. If desired, ad-

jacent trucks can be caused to abut one another end to end so that theintroduction of one truck into the preheating section will cause all yofthe preceding trucks within `the furnace to be moved along a distanceexactly the length of one truck. Consequently, as one truck isintroduced into the forward end of the furnace, another truck will bepushedfrom-the exitend thereof.

together with an interposed sheet of non-brittle material to formcomposite glass. The bending of the sheets in pairs insures that the twosheets will have the same curvature and thus reduces breaking of theglas incident to compositing to a minimum. -f

While certain temperatures havebeen mentioned hereinabove, it is to beunderstood that these have been given 'merely'by way of example and thatthe temperatures in different portions of the furnace may be varied,depending upon the length of the furnace sections, thickness of theglass blanks, etc. Furthermore, the invention is not limited to thespecific means disclosed for heating the bending section of the furnace.

It is also to be understood that the form of the invention herewithshown and described is to be taken as the preferred embodiment of Ithesame, and that various changes in the shape, size and arrangement oflparts mayy be resorted to without departing from the spirit of theinvention or the scope of the subjoined claims.

1. In an apparatus for bending fiat or substantially at blanks of glass,a continuous bending furnace of tunnel construction including apreheating section, a bending section, and a cooling section arranged insubstantial alignment with and constituting substantial continuations ofone another, molds for supporting the blanks to -be bent, means forcarryingvthe molds and blanks successively through said preheating,bending and cooling sections, said blanks being preheated withinV saidpreheating section and subsequently cooled' in said cooling section,means forsubjecting the blanks to a bending. heat within said bending'section, thereby causing the said blanks to drop by their own weight andtake the shape of the molds, means associated with the said preheatingsection of the furnace for withdrawing a portion of the heat from thesaid` bending section and utilizing it to effect the preheatingoperation, and a vertically movable plunger operating through an openingin the Vroof of the cooling section of the furnace for effecting amechanical pressing of the said blanks as they leave the bending sectionto force them into intimate contact with the molds.

2. lin an apparatus for bending flat or substantially fiat blanks ofglass, a continuous bending furnace of tunnel construction including apreheating section, a bending section, and a cooling section, molds forsupporting the blanks to' be bent, means for carrying the molds andblanks successively through said preheating, bending, and coolingsections, said blanks being preheated within said preheating section andsubsequently cooled in said cooling section, means forsubjecting theblanks to a bending heat within said bending section, thereby causingthe said blanks to drop by their own weight and take the shape of themolds, and a vertically movable pressing member operating through anopening in the roof of the cooling section of the furnace for eifectinga mechanical pressing of the said blanksas they leave the bendingsection to force them into intimate contact with the molds.

3. In'an apparatus for bending at or substantially fiat blanks ofglassto a predetermined curvature, a continuous tunnel furnace including apreheating portion, a bending portion, and a cooling portion arranged insubstantial horizontal alignment, molds for supporting the blanks to bebent and having curved mold faces, means for passing the molds andblanks successively through said preheating, bending and coolingportions, said blanks being preheated within said preheating portion andsubsequently cooled in said cooling portion, means for subjecting theblanks to a bending heat Within said bending portion, thereby causingthe said blanks to drop and take the shape of the molds, meanscornmunicating with the preheating portion for creating a draft withinthe bending portion whereby to Withdraw a portion of the heat from saidbending portion and cause it to flow longitudinally through saidpreheating portion in a direction opposite to the direction of movementof the molds and blanks therethrough, and means communicating with thebending portion at the end thereof remote from the preheating portionserving to create a draft in the said bending portion to counteract theWithdrawal of the heat therefrom into the said preheating portion.

4. In an apparatus for bending flat or substantially flat blanks ofglass to a predetermined curvature, a continuous tunnel furnaceincluding a preheating portion, a bending portion, and a cooling portionarranged in substantial horizontal alignment, molds for supporting theblanks to be bent and having curved mold faces, means for passing themolds and blanks successively through said preheating, bending andcooling portions, said blanks being preheated Within said preheatingportion and subsequently cooled in said cooilng portion, means forsubjecting the blanks to a bending heat Within said bending portion,thereby causing the said blanks to drop and take the shape of the molds,means mounted in the forward end of the cooling portion for effecting amechanical pressing of the said blanks subsequent to thev bendingthereof but While they are still in a highly heated condition to forcethem 'into intimate contact with the molds, means communicating with thebending portion at the end thereof remote from the preheating portionserving to create a draft in the said bending portion lto counteract theWithdrawal of the heat therefrom into the said preheating portion.

DAVID H. GOODWILLIE.

